Cisco Cisco IP Contact Center Release 4.6.2 Design Guide

Separate paths must exist from agent sites to each central site. Both paths must be capable of 
handling the full load of signaling, media, and other traffic if one path fails. These paths may reside 
on the same physical link from the agent site, with a WAN technology such as Frame Relay using 
multiple permanent virtual circuits (PVCs).

The minimum cluster size using Unified IP IVR as the treatment and queuing platform is 5 nodes 
(publisher plus 4 subscribers). This minimum is required to allow Unified IP IVR at each site to 
have redundant connections locally to the cluster without traversing the WAN. JTAPI connectivity 
between Unified CM and Unified IP IVR is not supported across the WAN in this model. Local 
gateways also will need local redundant connections to Unified CM.

The minimum cluster size using Unified CVP as the treatment and queuing platform is 3 nodes 
(publisher plus 2 subscribers). However, Cisco recommends 5 nodes, especially if there are phones 
(either contact center or non-contact center) local to the central sites, central gateways, or central 
media resources, that would require local failover capabilities.

In a deployment with clustering over the WAN, the VRU PG could connect to a local IP IVR or 
Unified CVP, or to a redundant IP IVR or Unified CVP across the WAN. For information on 
bandwidth requirements, refer to the chapter on 

.

In this model, the voice gateways are located in the central sites. Unified IP IVR is centrally located and 
used for treatment and queuing on each side. 

 illustrates this model.

ICCS

ICM Public

ICM Private

1

2

3

126025

ICM

A

4

5

ICM

B